AuthorTopic: HMS Lundon (Read 19805 times)

You should be able to calculate quite accurately the displacement of the items that sit above the waterline and then see if that works with your tanks volume.

The wet sections can be calculated by laying out the area of the superstructure that projects above the waterline and assuming a material thickness to obtain volume. In truth the material thickness may vary a little especially if it's a hand laid laminate, however you should get within 10-15% of the true figure, and that IMo is good enough to see that you're on the right track.

If you use a good quality epoxy laminate for the upper structure, a laminate thickness of about 1mm is perfectly acceptable, and for smaller structures like the conning tower 0.5mm would be adequate, although it would require careful work to make a strong composite at those thicknesses. If you use polyester resin for a laminate, I would double those figures, as polyester resin is weaker and more prone to warping than epoxy therefore requires a bit more bulk.

Some hull shapes can be very tricky to layout, e.g. WWII type subs with their complex superstructures which curve and weave around. Modern subs tend to have simpler geometry, so that makes life easier.

You could use laminate but you could also consider a 100% scale material - sheet steel in the form of tinplate.

Advantages are:- best strength and weight for a material with minimum displacement.- from a scale point of view, free flooding holes look much more realistic than glass fibre which looks too thick.- can be easily cut (old scissors) and soft soldered (use a +50 watt iron)- would fit neatly into your college workshop sessions.- quite good for WW1 & 2 subs with simple curves (not easy with compound curves e.g modern nukes.)- Your original drawing shows a fairly simple superstructure with a relatively simple fin (conning tower) - so it may be suitable.

Disadvantages:- Can be a seen as a little bit "retro" for a modelling material. Although subs are a special category and I see a recent article in "Model Boats" restating the benefits of tinplate.- You can't get moulded surface detail.- Sheet tinplate is less easy to obtain than you may think. (Biscuit tins have long gone. You can get thin sheets from RS Components. ) If you can't get tinplate you can use brass sheet - more expensive but can give stunningly realistic appearance . (Reference my fellow club member Dave J's models)

Although low in displacement, steel and brass are very dense- at least four times the density of an equivalent thickness laminate. I'd be thinking anything less than 0.5mm thick sheet could be tricky to work with, so that would be at least twice the weight of a 1mm GRP laminate and considerably less rigid. Aluminium is much lighter, but much weaker and difficult to solder, although you can epoxy it together.

So be mindful of top weight causing stability issues if things are getting a bit marginal.

I will get going with the calculations of upper structure volume/mass.

The sheet steel is an interesting solution, but unfortunately I don't posses any experience..Which me and a friend do have, when it comes to epoxy laminate and carbon fibre (which I wont use but similar process).

I'm leaning towards some type of epoxy laminate for the structure above waterline. With "plugs" and molds. A bit time consuming, but worth it.Probably epoxy laminate for the aft and stern sections too.

Will get going with the molding in the weekend, primarily the aft and stern. Awaiting an order from engel-modellbau with rubber bellows and u-joint couplings. When it arrives, I will be able to finish the "end-cap" and then do some water testing. Either reuse the old rc-kit from the old submarine or buy a new one for the testing.

I would like to once again announce a big thanks to GPA-Plast in Hjärnarp Sweden and Carlsson & Möller in Helsingborg Sweden, for their help with providing material for the submarine and thereby helping me keeping the costs down.

Hello,Did not get much done last weekend, but this weekend looks promising!Foam core for the plug

Some putty(?) on

Lots of leftover epoxy that will be sanded of/refinforced with more..A bit worried about the rubber bellows, they fit perfect on the pushrods but a bit to loose on the brass pipes.How do you all fit them secure? At the moment I have secured them with cable ties..

Had a left over brasspipe that fits perfect as protection.

hehe

hose clamp, will it be enough you think? (Got these at all connections with water in/out-lets)

That's a very good set. Before the advent of 2.4ghz I used a RD6000 on 35mhz for aeroplanes, which served me very well. The only thing I would say, is that the control layout may not suit your boat very well, as it looks like all the functions beyond the sticks are switched. Generally we require a set with a rotary or linear slider for some of our controls. Older analogue sets could be adapted to suit, but a lot of the later digital sets are bit more restrictive. So it pays in the long run to look carefully at the set you purchase.

Two or three years ago many suppliers were clearing their stock of 40mhz kit, and there was a lot of very good equipment going for what must have been close to cost price. However those days are now gone, and therefore secondhand units off ebay and small ads are the best way to get cut price radio on the lower frequency bands. I do find that receivers tend to be easier to get hold of than transmitters.

That's a very good set. Before the advent of 2.4ghz I used a RD6000 on 35mhz for aeroplanes, which served me very well. The only thing I would say, is that the control layout may not suit your boat very well, as it looks like all the functions beyond the sticks are switched. Generally we require a set with a rotary or linear slider for some of our controls. Older analogue sets could be adapted to suit, but a lot of the later digital sets are bit more restrictive. So it pays in the long run to look carefully at the set you purchase.

Thanks for the input! I think I will place an order on the Sanwa. Will give it some thought first.

Tomorrow soldering will begin. Santa stopped by my place, dressed in a DHL costume, and handed over a brand new RC unit from Sanwa which thus far works well (haven't tried all the cool features yet..).A proper update with pictures and all will be uploaded tomorrow, but here is a teaser..

*EDIT*I would like any good advices on how to solve the servos "twitching". At the moment 2 channels are combined with a V-tail mixer, the two outgoing channels from the v-tail mixer is then split too 4 servos. I suspect the V-tail combined with splitting is what makes them twitching. There is an built-in V-tail solution in the radio which I will try to explore further.